Introduction 

Bacteria are remarkable organisms that can confer numerous benefits to your body. However, under certain conditions, the bacteria residing in your body can become opportunistic and cause insidious infections. For instance, bacteria that cause flesh-eating disease can be found on the skin. This flesh-eating disease, also referred to as necrotizing fasciitis, causes death of tissues and inflammation of the fascia. When the skin is injured in abrasions or minor cuts, the bacteria can invade the deep layers of the skin, causing necrotising fasciitis and extensive tissue death. 

Furthermore, these bacteria sometimes do not work alone. They can join forces with other bacterial species and cause a rare and deadly form of necrotising fasciitis called Fournier Gangrene. This is a rapidly progressive and fatal disease that affects the anal, scrotal and genital regions. It commonly occurs in older men, people with diabetes and less frequently, in women and children. This article reveals the spine-chilling microbiology of Fournier’s gangrene infections.   

What is Fournier Gangrene?

Fournier Gangrene is a type of necrotising soft tissue infection (NSTI) that affects the scrotum, penis, perineal and perianal regions.¹ It was discovered in 1883 by a French venereologist, Jean Fournier.² It is a rapidly progressive disease characterised by infection of the soft tissues by the synergistic action of various pathogens that extend along fascial planes, causing necrosis of these tissues and subsequent tissue death.³ This necrosis occurs immediately after the formation of blood clots in the small vessels, which is due to endarteritis obliterans caused by the invasion of the pathogens in the subcutaneous tissues.³ The necrosis usually originates from an infection, cut or wound in the urogenital tract or the skin of the genitalia.⁴ 

Fournier Gangrene is commonly seen in people assigned male at birth (AMAB) between the ages of 40-70 years old. However, it is a very rare and fatal form of necrotising fasciitis, with an incidence rate of 1.6 per 100,000 males.⁵ Also,  the male-to-female ratio is approximately 10:1. Lower incidence in females may be related to better drainage of the perineal region via vaginal secretions. Furthermore, homosexual men may be at higher risk, especially to drug-resistant strains of causative agents.⁶ 

Risk Factors of Fournier Gangrene

Fournier Gangrene is a polymicrobial aerobic, anaerobic and microaerophilic synergistic infection originating from the colorectal, genitourinary or skin infection site. The comorbid predisposing factors associated with this disease include:

• Diabetes
• HIV
• Morbid obesity 
• Cirrhosis
• Chronic alcoholism 
• Renal failure 
• Lymphoproliferative diseases
• Chronic steroid use
• Malnutrition¹¹ 

However, people without a medical history can also develop this condition, though with a less severe outcome.¹¹

How Fournier Gangrene Infection occurs

The pathogenesis of Fournier gangrene infection stems from certain etiologic factors such as infection in the perineum, perianal abscess, long-dwelling catheter, ulcers and external trauma that provide the portal of entry for the causative microorganisms. People who are immunocompromised due to comorbidities such as diabetes, HIV, renal failure, obesity, chronic alcoholics develop a primary infection site such as an abscess.⁷ The compromised immunity provides a conducive environment to initiate infection, followed by the rapid spread of the disease due to the virulence of the microorganisms. The virulence of these microorganisms occurs due to the production of toxins and enzymes that create a favourable environment for microbial multiplication.⁶ 

These microbial weapons (i.e., toxins and enzymes) cause ischemic gangrene of the overlying skin in the involved structures. The enzymes produced by these organisms can also cause thrombosis of the nutrient vessels, limiting their blood supply. The reduced oxygen supply to the tissues promotes the growth of anaerobic and microaerophilic organisms and fascial necrosis. These latter organisms may further produce enzymes (e.g. collagenase), which digest the fascial barrier, accelerating the rapid spread of the infection.⁸ The anaerobic bacteria can also produce nitrogen and hydrogen, which can accumulate in the tissues and cause crepitation.⁸

Causative Organisms of Fournier Gangrene 

The main aetiological organisms of Fournier Gangrene are Escherichia coli and Bacteroides species. The former is the predominant aerobe, and the latter, the predominant anaerobic bacteria. Other common pathogens include Proteus, Staphylococcus, Enterococcus, aerobic and anaerobic Streptococcus, Pseudomonas, Klebsiella, and Clostridium. Also, methicillin-resistant Staphylococcus aureus (MRSA) isolates can be found.⁹ These bacteria can invade the body via several sources, including urinary, bowel, or dermal, through a surgical wound or cut. Urinary tract infections and other infections such as perianal abscesses can also serve as a starting point for this condition.

The clinical presentation of Fournier Gangrene includes moderate to severe pain in the genitalia. Initially, only the scrotum is involved, but if uncontrolled, the bacterial skin infection spreads until the entire scrotal region is affected, leaving the testes exposed but appearing healthy.¹⁰ One overwhelming and distinctive feature of the presentation is a strong, putrid and repulsive smell that is associated with the condition.¹⁰ Other varying signs and symptoms include fever, swelling of the scrotum and erythema, purulence and crepitation.¹⁰ 

Diagnosis of Fournier Gangrene

Fournier Gangrene is diagnosed mainly based on clinical findings. These clinical findings include pain, swelling and wounds in the genitalia and perineum.¹²  Detection of fluctuance, crepitance, localised tenderness and wounds also raises the possibility of fournier gangrene. Use of radiological tools to determine the extent of the disease is also employed.⁶ These tools include ultrasound scan (USS), computed tomography (CT) and magnetic resonance imaging (MRI).⁶ 

USS reveals subcutaneous emphysema, a thickened fluid-filled scrotal wall and in differentiating necrotising infection from other scrotal pathology. The main role of a CT scan is in detecting the origin of infection and determining the extent of the disease. The level of fascial destruction has been shown to correlate with the total affected area at surgery.¹³ MRI also enables the detection of subcutaneous emphysema and provides a wider view and accurate assessment of the spread of infection and fluid accumulation.¹ The hallmark of all these imaging techniques is the demonstration of air in the soft tissue planes.⁶

Treatment Options and Management of Fournier Gangrene

The treatment of Fournier gangrene depends on the clinical presentation when you visit the hospital. However, the cornerstone of treatment for this condition is surgical debridement of all necrotic tissues using high doses of broad-spectrum antibiotics.⁸ Immediate treatment following diagnosis includes resuscitative procedures like rehydration, blood transfusion, replacement of electrolytes, use of albumin and vasopressors and hyperbaric oxygen therapy.⁶ 

Broad spectrum antimicrobial therapy is commenced empirically to cover aerobes, anaerobes, Gram-positive and Gram-negative organisms. This is done pending when the result of microscopic examination, culture and antibiotic susceptibility testing is concluded.⁶ Colostomy can be used for faecal diversion in cases of severe perineal involvement. The rationale behind colostomy is to reduce the number of germs in the perineal region and enhance the wound healing process.⁸ Urinary diversion might be needed if there is extensive urethral or penile involvement though urinary catheterization is done in most cases.⁸ 

Emerging therapies include topical treatment, involving the use of honey, which inhibits the growth of bacteria due to its low pH of 3.6.⁸ Honey also contains enzymes that digest necrotic tissues and bacteria. Hyperbaric oxygen therapy is considered to be an appropriate adjunct to surgical debridement and broad-spectrum antimicrobial therapy. This is because it provides adequate oxygenation for optimal phagocytic function of neutrophils, inhibition of the growth of anaerobes and increased intracellular antibiotic uptake.¹⁴ Plastic reconstruction may be required to restore function and provide skin cover. This includes transplantation of testis, skin grafts and myocutaneous flaps. Split thickness skin graft (STSG) has been studied to be the treatment of choice for perineal and scrotal skin defects.⁸

FAQs

What are the complications associated with Fournier Gangrene? 

Given the devastating symptoms Fournier Gangrene confers on patients, the systemic complications include acute renal failure, acute respiratory distress syndrome, cardiac arrhythmias, heart failure, multiple organ failure, and bacteremia.

How can you prevent Fournier Gangrene?

You can prevent Fournier Gangrene by maintaining a healthy weight, reducing the use of tobacco products, taking care of wounds and cuts, and observing good hygiene, especially in the genital areas. 

Does diabetes cause Fournier Gangrene? 

Fournier Gangrene occurs due to a variety of risk factors. However, diabetic patients have an increased risk of developing this disease due to compromised immunity, poor wound healing and use of a group of diabetes medications called sodium-glucose cotransporter-2 (SGLT2) inhibitors. 

Summary

• Fournier Gangrene is a rare, fulminant and highly lethal polymicrobial infection of the perineum, perianal and genital regions
• It occurs when the host immunity is compromised by health conditions. This allows the entry of synergistic microorganisms to thrive, producing enzymes and toxins that cause insidious symptoms associated with the condition
• Given the rapid progression of this infection, early diagnosis is paramount to control the devastating symptoms caused by the organisms, which can include sepsis leading to multi-organ failure
• The most effective treatment procedure involves aggressive surgical debridement of all necrotic tissues and use of broad-spectrum antibiotics
• Maintaining good hygiene, treating wounds and proper skin care can also prevent Fournier Gangrene as skin cuts serve as the primary portal of entry of microorganisms and subsequent onset of the disease